I'd leave it alone, then. At most, replace the tailpipes with something equal to the rest of the system. The change from 289 to 302 is insignificant by itself. If you've gone from a stone-stock 289 2V to a wild modified 302, that's important.

 

I'm actually going from a mild mod I6 to the 302.

I'm glad I don't have to replace the exhaust system, I wouldn't have the money to do so in my time period. I've got just under 3 weeks to finish it.

 

IMO 2" is too small but with your next major mod/upgrade switch to a bigger exhaust like 2.5"

 

Since the motor is not stock my best recommendation is 2 1/4. However depending on the compression of the motor I would consider a 2.5 inch exhaust if it is a high compression motor.

Also If you do plan on changing the exhaust plan ahead. If you plan to put any power adders to your stang i would highly recommend just getting 2.5 in. exhaust if you do change it now.

 

Looks like I'll be using money over the summer to get a good exhaust system. Will eventually go to long tube headers, right now I'm stuck with the stock ones from 87.

Eventually I was thinking about adding a supercharger or a NOS kit to it.

 

Yeah I'm not sure if I can use them when I go bigger. They guy did actually weld them to my pipes unfortunately. They are also the GT repro tips so the inlet is only like 1.75"



I really like the sound of Borla exhaust, its tempting to just save up and buy their mufflers and then have the exhaust guy run the rest for me. Just have to really think if I want to spend almost $200 per muffler.

 

You can certainly use the exhaust you have but it will be costing you some power....I noticed a pretty good gain on my mustang when it had a 302 in it just by going from 2 1/4 to 2 1/2....I also changed to some very free flowing mufflers at the same time and altogether I picked up close to 3 tenths in the 1/4 mile which is pretty good..

 

I'm with JMD. At least for now stick with your current exhaust since it's not very old. But yeah maybe in the summer you can switch.

 

If it's that new I wouldn't bother with the expense of changing now but I would upgrade the parts that you are changing if they can stay for the next upgrade. Maybe go 2 1/4" or 2 1/2" from the headers to X with reducers. If the X is 2" then you could always cut and go from the header reducers back.
I doubt you'll see much seat of pants differrence between a 2" vs. 2 1/4 or 2 1/2 system on a motor with stock heads.

The important place for mandrel vs. crush bend is over the axle where it makes almost 4 90* bends, this is where the crush sysems get small. I haven't seen any local shops set up to do mandrel bends, the machine is very expensive and usually only owned/used by exh. manuf. like flowmaster, magnaflow, etc. All the exhaust shops I've seen just have a tubing bender (crush).
Jon

 

Borla is nice, but I can't see spending more than 100 per muffler.